Liquid Chromatographic Determination of Dimetridazole and Ronidazole in Feeds

Abstract

A simple high performance liquid chromatographic (HPLC) procedure for the simultaneous determination of dimetridazole and ronidazole in turkey feeds is described. The drugs are extracted from feeds by carbon-tetrachloride/dimethylformamide (80:20) at 60°C during 30 mn and the extract is subjected to a partition by water. After centrifugation the eluate is chromatographed on a reverse phase column with ultaviolet detection at 316 nm. Recoveries from samples fortified at levels 2.02 to 7.07 ppm for ronidazole and 2.01 to 7.03 for dimetridazole were 99,6% ± 1,4 and 95,3% ± 1,8 (mean ± standard deviation), respectively.     

An Improved Method for the Determination of Reserpine in Plasma Using Liquid Chromatography with Fluorescence Detection

Abstract

A liquid chromatographic method coupled with fluorescence detection was developed to measure plasma reserpine concentrations. After extraction from 3 ml of plasma, the reserpine and internal standard (methyl-18-triethoxy benzoyl reserpate) residues were oxidized to their respective fluorophors by vanadium pentoxide and chromatographed on a reversed phase trimethylsilyl column. These compounds were detected at excitation wave length 460 nm and analyzed at 570 nm. The minimum quantifiable level was ca 0.3 ng/ml and the absolute recovery was determined to be between 78–83%. The coefficient of variation was less than 9% for day-to-day and within run analyses. This method is suitable for pharmacokinetic studies of reserpine in man.     

Use of Ethoxy-Homologs as Internal Standards for Determination of Urinary Vanillylmandelic Acid and Normetanephrine in Man by High Performance Liquid Chromatography

Abstract

Synthesis of the ethoxy-homologs of vanillylmandelic acid (3-ethoxy-4-hydroxymandelic acid, EMA) and normetanephrine (3-ethoxy-4-hydroxyphenylethanolamine, EHPEA) and their use in minor modifications of existing assays on human urine are described. For analysis of vanillylmandelic acid, the homologous internal standard is added to an aliquot of urine, organic acids are then extracted into ethyl acetate and back extracted into 10% K₂CO₃, and finally extracted a second time into ethyl acetate. After evaporation of the ethyl acetate, the residue is redissolved in the mobile phase to be used in the chromatography, and injected onto a reverse phase column. Comparison of results with a gas chromatography-mass spectrometry (GCMS) assay gave almost identical results (96% ± 2%, mean ± SE, n=10). Analysis of normetanephrine is performed by addition of internal standard to an aliquot of urine before heat hydrolysis of amine conjugates. The amines are adsorbed onto columns of Bio Rex 70, and then eluted with a solution of 1 M NH₄OH, which is then evaporated to dryness. After residue is redissolved in borate buffer, the amines are extracted into toluene:isoamyl alcohol and back extracted into 0.1 M acetic acid before injection onto a reverse phase column. Correlation with a GCMS assay gave similar results (102% ± 4%, mean ± SE, n=9).     

Urease inhibitory potential of extracts and active phytochemicals of Hypochaeris radicata (Asteraceae)

Abstract

Urease inhibition potential of compound (1), guaiane-type sesquiterpene (2), confertin (3) and scopoletin (4) was carried out with high throughout mechanism-based assay. These compounds were isolated from Hypochaeris radicata L., an Asteraceae family member. The pure compounds were screened for their urease and carbonic anhydrase inhibitory activities. The ethyl acetate fractions were subjected to column chromatography, which resulted in the isolation and purification of four compounds (1–4). On evaluation, compounds (1–4) exhibited selective activity against urease enzyme with an IC₅₀ value of 180.11 ± 2.00, 27.18 ± 0.80, 24.12 ± 0.2 and 30.12 ± 1.10 µM respectively. The compounds (1–4) were found to be inactive against carbonic anhydrase enzyme. Thiourea was used as standard inhibitor (21 ± 0.14 µM) of urease enzyme.     

Determination of Reserpine in Plasma Using High-Performance Liquid Chromatography with Fluorescence Detection

Abstract

A high-performance liquid chromatographic method for determining reserpine in plasma has been developed. The procedure involves extraction of reserpine from buffered plasma into benzene, oxidation of reserpine to a fluorophor by treatment with vanadium pentoxide in phosphoric acid, and chromatographic separation of the reserpine fluorophor on an octadecylsilane column by ion-pairing with heptanesulfonate ions. Fluorescence monitoring of the column effluent provides high sensitivity of detection and increases the specificity of the procedure. A detection limit of approximately 100 pg of reserpine per ml of plasma was obtained following analysis of 2 ml samples. Analysis of a number of samples demonstrated the applicability of this method in confirming the presence of reserpine in equine plasma specimens collected at various horse shows and in evaluating the pharmacokinetic behavior of reserpine following intramuscular administration to horses.     

Determination of Reserpine in Urine by Capillary Electrophoresis with Electrochemiluminescence Detection

A fast and sensitive approach to detect reserpine in urine using micellar electrokinetic capillary chromatography with electrochemiluminescence (ECL) of Ru(bpy)₃²⁺ detection is described. Using a 25 μm i.d. capillary as separation column, the ECL detector was coupled to the capillary in the absence of an electric field decoupler. Field‐amplified injection was used to minimize the effect of ionic strength in the sample and to achieve high sensitivity. In this way, the sample was analyzed directly without any pretreatment. The method was validated for reserpine in the urine over the range of 1×10^?6?1×10^?4 mol/L with a correlation coefficient of 0.996. The RSD for reserpine at a level of 5 μmol/L was 4.3%. The LOD (S/N=3) was estimated to be 7.0×10^?8 mol/L. The average recoveries for 10 μmol/L reserpine spiked in human urine were 94%.     

Ion Chromatographic Determination of Traces of Sodium,Magnesium and Chlorine in Gadolinium Nitrate

Abstract

Two independent and sensitive ion chromatographic methods with suppressed conductivity were developed for determination of traces of Cl, Na, and Mg in gadolinium-nitrate. Na-Mg was determined by cation-exchange column after matrix separation, whereas Cl was analyzed without matrix separation by high capacity anion-exchange column. Detection limit for Cl was 0.01 µg mL^?1 in sample solution and 1 µg g^?1 in solid sample. The reproducibility (100 µL injected) was better than 3%, 3% and 4% at 50, 25 and 50 µg L^?1 level for Cl, Na, and Mg respectively. The overall precision was better than ±7% for Na-Mg and ±5% for Cl.     

Determination of Prifinium Bromide in Six Pharmaceutical Formulations by Reverse-Phase Hplc

Abstract

Prifinium bromide is an anti-cholinergic drug, available commercially in various pharmaceutical formulations such as tablets, suppositories, syrups, and ampoules. The present available analytical methods are time-consuming and range from non-aqueous titration to UV-spectrophotometry to ion-pair visible spectrophotometry. The method reported here is a fast, reliable, and stability-indicating reversed phase HPLC for prifinium bromide in its various pharmaceutical formulations. The mobile phase was 0.03 M ammonium acetate in acetonitrile: water (65:35); the pH was adjusted to 4.0 with glacial acetic acid. The column utilized was (250 mm × 4.6 mm i.d.) Supelcosil LC-8-DB (5μ) and detection was carried at 254 nm. Benzophenone was used as internal standard. The assay was applied to commercial products and the results expressed in (% label claim ± RSD) are (99-58 ± 0.36), (100.50 ± 0.40), (99-95 ± 0.70), (99. 94 ± 0.29), (100.28 ± 0.52), and (99-99 ± 0.57) for six commercial formulations. The method was tested for linearity, recovery, and specificity and was found fast, stability-indicating, and free from interferences. The method can be extended to separate     

Analysis of Thyroidal Amino Acids in Pharmaceutical Preparations. I - Reverse Phase High Pressure Liquid Chromatography Analysis of Sodium Liothyronine from Tablets

Abstract

A simple, sensitive and specific assay method was developed for the assay of sodium liothyronine (T₃Na) from tablets. Sodium liothyrorn'ne was extracted from powdered tablets with a solvent system consisting of butanol and dilute hydrochloric acid. The solvent was removed under vacuum and the residue was dissolved in ammonical methanol. An aliquot of this solution was injected on a μBondapak C₁₈ column and the elution was carried out with a mobile phase consisting of methanol:water:phosphoric acid (55:45: 0.1). The effluent was monitored by U. V. detection at 254 nm. A linear calibration curve was obtained in the range of 10 to 250 ng on column with a precision of ±4% (C. V.). The internal standard consisted of 3, 3′, 5-triiodothyronine (T3′ or RT₃). The usefulness of an alternate compound, 3, 5-diiodo-3′, 5′-dibromothyronine, which is not endogenous, was also demonstrated as an internal standard.     

A Rapid HPLC Analysis of Diazepam in Animal Feed

Abstract

A rapid HPLC analysis is described for the methanolic extraction of diazepam from spiked animal feed. A short disposable reverse-phase extraction column is employed to remove interfering substances present in the animal feed. This is followed by direct injection of an aliquot into an analytical ODS column. The precision is better than 3.9% and the % recovery is 87.8 ± 0.8% resulting in a convenient, rapid method for the routine analysis of added diazepam in prepared animal diets.     

Officinalioside,a new lignan glucoside from Borago officinalis L.

A new lignan glucoside, officinalioside (1), was isolated from n-BuOH fraction of the aerial parts of Borago officinalis L., together with four known compounds: actinidioionoside (2), roseoside (3), crotalionoside C (4) and kaempferol 3-O-β-D-galactopyranoside (5). The structure of the new compound was established by means of spectroscopic and chemical analyses. Compounds 1 and 2 showed a moderate DPPH radical scavenging activity (IC₅₀: 52.6 ± 1.70 and 41.3 ± 0.25 μM, respectively) comparable with that of the standard trolox (16.6 ± 2.2 μM) without any significant cytotoxicity towards human cell line A549 (IC₅₀ > 100 μM).     

New macrocyclic diterpenes from Euphorbia connata Boiss. with cytotoxic activities on human breast cancer cell lines

Acetone:chloroform (1:2) extract of the aerial parts of Euphorbia connata Boiss. (Euphorbiaceae) was investigated for its diterpenoids. This led to the isolation of one known and two new diterpenes, belonging to the pentahydroxy-13(17)-epoxy-8,10(18)-myrsinadiene and tetrahydroxy-5,6-epoxy-14-oxo-jatropha-11(E)-ene classes. The structures were elucidated based on ¹³C and ¹H NMR as well as 2D NMR, IR and MS spectra and the cytotoxicity for compounds 1–3 were evaluated by using MTT assay against two human breast cancer cell lines. Myrsinane-type compounds – 3,7,14,15-tetraacetyl-5-propanoyl-13(17)-epoxy-8,10(18)-myrsinadiene (1) and 3,7,10,14,15-pentaacetyl-5-butanoyl-13,17-epoxy-8-myrsinene (2) – exhibited moderate inhibitory effects, with IC₅₀ values of 24.53 ± 3.39 and 26.67 ± 1.41 μM against the MDA-MB cell line, and 37.73 ± 3.41 and 34.57 ± 2.12 μM against the MCF-7 cell line, respectively. Jatrophane-type diterpene – 5,6-epoxy-8,9,15-triacetyl-3-benzoyl-14-oxo-jatropha-11(E)-ene (3) – showed weak cytotoxicity, with IC₅₀ values of 55.67 ± 7.09 μM against MDA-MB, and moderate cytotoxicity with IC₅₀ values of 24.33 ± 3.21 μM against MCF-7 cell line.     

Anti-glycating and anti-oxidant compounds from traditionally used anti-diabetic plant Geigeria alata(DC) Oliv. & Hiern.

Abstract

A new sesquiterpene lactone geigerianoloide (1) and four known flavonoids axillarin (2), quercetin (3), 3-methoxy-5,7,3',4'-tetrahydroxy-flavone (4) and hispidulin (5) were isolated from Geigeria alata (DC) Oliv. & Hiern. (Asteraceae). Structures were deduced using ¹H- and ¹³C- NMR spectroscopy, mass spectrometry, while the structure of compound 1 was also deduced using X-ray crystallography technique.

Geigeria alata is traditionally used for diabetes, therefore compounds were tested for anti-glycation activity, in which compounds 2 and 3 showed potent activities (IC₅₀ values of 246.97?±?0.83 and 262.37?±?0.22 µM, respectively) compared to IC₅₀ value 294.50?±?1.5 µM of rutin. Moreover, compound 4 exhibited a comparable activity to rutin (IC₅₀?=?293.28?±?1.34 µM). Compound 5 showed a weak activity.

Compounds 2, 3, and 4 exhibited potent DPPH radical scavenging activity (IC₅₀?=?0.1?±?0.00, 0.13?±?0.00 and 0.15?±?0.01 µM, respectively). Compounds 2, 3, and 4 demonstrated significant superoxide anion scavenging activity with IC₅₀ values of 0.14?±?0.001, 0.17?±?0.00, and 0.11?±?0.006 µM, respectively.     

Development and validation of rapid HPLC method for determination of doxofylline in bulk drug and pharmaceutical dosage forms

A simple, selective, rapid, and economical reversed phase high performance liquid chromatography(RP-HPLC) method for the determination of doxofylline in the commercial dosage form has been developed and validated. The separation and quantification were achieved on an HiQ Sil C 18 W column using a mobile phase of acetonitrile: buffer (50: 50), pH 3, at a flow rate of 1 mL/min with detection of analyte at 272 nm. The separation was achieved within 3.1 ± 0.3 min for doxofylline sample. The method showed good linearity in the range of 10–80 μg/mL. The intra and inter day RSD ranged from 0.37–0.53%. The recovery (mean ± S.D.) of low, middle and high concentrations were 100.04 ± 0.80, 100.01 ± 0.20, 100.07 ± 0.30 respectively. Limit of detection and limit of quantification were 0.03 and 0.1 μg/mL, respectively.     

New jacaranone glucoside from Jacaranda oxyphylla leaves

Jacaranda oxyphylla Cham. is popularly known as ‘caroba-de-São-Paulo’ and it is used in traditional medicine for microbial infections. A new phytoquinoid (α/β-glucoside-4-phenylacetate-6-(1-hydroxy-4-oxo-2,5-cyclohexadiene-1-acetate) (1) was isolated from J. oxyphylla leaves, together with three known compounds: quercetin-3-O-β-d-galactoside (2), verbascoside (3) and polystyrene (4). Their chemical structures were elucidated using spectroscopic techniques and by comparison with the related known compounds. In addition, it was found a pronounced acetylcholinesterase inhibitory activity for the quinoid 1 (100.0 ± 0.8%) and phenolic compounds 2 and 3 (99.9 ± 0.7 and 99.3 ± 0.5%, respectively), if compared to the standard eserine (92.7 ± 0.4%), that was analysed by a microplate spectrophotometer.     

Simultaneous determination of six free fatty acids in alcohol extract of <Emphasis Type="Italic">P. japonicus</Emphasis> C. A. Mey. van <Emphasis Type="Italic">major</Emphasis> (Burk.) C. Y. Wu et K. M. Feng by gas chromatography-mass spectrometry

P. japonicus C. A. Mey. var. major (Burk.) C. Y. Wu et K. M. Feng is an important medicinal plant and has special beneficial effects on human health. Six types of free fatty acids (FFAs) were identified and quantified in the alcohol extract of P. japonicus C. A. Mey. var. major with a GC-MS method, including two fatty acids essential to the human body. All the six FFAs identified in alcohol extract were quantified using nonadecanoic acid as an internal standard. The results showed that the alcohol extract was abundant in four types of FFAs, unsaturated FFAs amounted to 47.04% of the total FFA content, and there were no trans FFAs. Palmitic acid (38.82%, 4.74 ± 0.09 mg/g) was the predominant fatty acid, followed by linoleic acid (27.92%, 2.31 ± 0.07 mg/g), stearic acid (14.14%, 1.54 ± 0.04 mg/g) and oleic acid (11.04%, 1.02 ± 0.03 mg/g).     

Estimation of Alprazolam and Sertraline in Pure Powder and Tablet Formulations by High-Performance Liquid Chromatography and High-Performance Thin-Layer Chromatography

Abstract

This article describes validated high-performance liquid chromatographic (HPLC) and high-performance thin-layer chromatographic (HPTLC) methods for simultaneous estimation of alprazolam (ALZ) and sertraline (SER) in pure powder and tablet formulation. The HPLC separation was achieved on a Nucleosil C18 column (150 mm long, 4.6 mm i.d., and 5-µm particle size) using acetonitrile and phosphate buffer (50 + 50 v/v), pH 5.5, as the mobile phase at a flow rate of 1.0 mL/min at ambient temperature. The HPTLC separation was achieved on an aluminum-backed layer of silica gel 60 F₂₅₄ using acetone/toluene/ammonia (6.0:3.0:1.0, v/v/v) as the mobile phase. Quantification with the HPLC method was achieved with ultraviolet (UV) detection at 230 nm over the concentration range 3–18 µg/mL for both drugs with mean recovery of 101.86 ± 0.21 and 100.57 ± 0.31% for ALZ and SER, respectively. Quantification in HPTLC was achieved with UV detection at 230 nm over the concentration range of 400–1400 ng/spot for both drugs with mean recoveries of 101.32 ± 0.15 and 100.38 ± 0.51% for ALZ and SER, respectively. These methods are rapid, simple, precise, sensitive, and are applicable for the simultaneous determination of ALZ and SER in pure powder and formulations.     

HPLC Quantification of Azintamide and Papaverine Hydrochloride Simultaneously in Pharmaceutical Preparations

Abstract

A simple HPLC-procedure for quantification of azintamide and papaverine. HCl simultaneouly in dosage formulations has been investigated. The complete resolution and quantitative determination of both drug substances has been undertaken on a Hibar 100RP-18 Lichrospher (5 μm) column by using a solvent mixture composed of acetonirile – water (56:44, v/v) isocratically at a rate of 1 ml·min^?1with UV-detection at 240 nm. Recovery percentages of 100.39 ± 0.70 (n = 12) and 99.97 ± 1.11 (n = 12) were obtained for added azintamide and papaverine. HCl, in order.     

Separation and Removal of Mercury(II) from Water Samples Using (Acetylacetone)‐2‐Thiol‐Phenyleneimine Immobilized on Anion‐Exchange Resin Prior to Determination by Cold Vapor Inductively Coupled Plasma Atomic Emission Spectroscopy

Abstract

(Acetylacetone)‐2‐thiol‐phenyleneimine (H₂L) immobilized on an anion‐exchange resin (Dowex) was used for separation and removal of mercury from natural water samples and for preconcentration prior to its determination by cold vapor inductively coupled plasma atomic emission spectroscopy. The metal was eluted from the column using a solution of 10% thiourea in 0.1 M HCl. The modified resin is higly selective with an exchange capacity of 1.60 mmol g^?1. Various parameters like pH, column flow rate, and desorbing agents are optimized. The proposed method has a linear calibration range of 15–1000 ng/ml Hg(II), with a relative standard deviation at the 15 ng/ml level of 3.5%. The precision of the method (evaluated as the relative standard deviation obtained after analyzing six series of five replicates) was ±4.2% at the 50 ng/ml level of Hg(II). The method has been used for routine determination of trace levels of mercury species in natural waters. The potential application of modified resin for the removal of mercury(II) from two natural water samples (top water and lake water) spiked with 50 ng/ml of mercury (II) was studied by ICP‐AES, and the results proved that excellent percent extraction of mercury(II) from both natural water samples was obtained by column method using modified resin.     

A Stability Indicating HPLC Assay for Prednisolone Sodium Phosphate in Implantable Infusion Pumps

Abstract

A stability indicting assay for prednisolone sodium phosphate (PSP) in solutions for implantable infusion pumps was developed. PSP and its major breakdown product, prednisolone, were separated from formulation excipients by reverse phase chromatography on a phenyl-bonded phase column using an acetonitrile-phosphate buffer mobile phase. Detection was by ultraviolet absorbance at 243 mm. Recovery from a synthetic formulation was 101.0 ± 0.4% (n=6). The method was used to monitor the stability of PSP solutions in implantable infusion pumps maintained at 37°C over a 21 day period.